## RYTWAYS Fresher Interview Questions with Answers – Part 2

### 6 . Write a Java program to swap two bits without using any variable .

 // C program to swap bits in an intger #include   // This function swaps bit at positions p1 and p2 in an integer n int swapBits(unsigned int n, unsigned int p1, unsigned int p2) {     /* Move p1’th to rightmost side */     unsigned int bit1 =  (n >> p1) & 1;       /* Move p2’th to rightmost side */     unsigned int bit2 =  (n >> p2) & 1;       /* XOR the two bits */     unsigned int x = (bit1 ^ bit2);       /* Put the xor bit back to their original positions */     x = (x << p1) | (x << p2);       /* XOR ‘x’ with the original number so that the        two sets are swapped */     unsigned int result = n ^ x; }   /* Drier program to test above function*/ int main() {     int res =  swapBits(28, 0, 3);     printf(“Result = %d “, res);     return 0; }

Output:

### 7 . Write a java program to swap two strings using a temporary variable .

 // Java program to swap two strings without using a temporary // variable. import java.util.*;   class Swap {         public static void main(String args[])     {         // Declare two strings         String a = “Hello”;         String b = “World”;           // Print String before swapping         System.out.println(“Strings before swap: a = ” +                                         a + ” and b = “+b);           // append 2nd string to 1st         a = a + b;           // store intial string a in string b         b = a.substring(0,a.length()-b.length());           // store initial string b in string a         a = a.substring(b.length());           // print String after swapping         System.out.println(“Strings after swap: a = ” +                                       a + ” and b = ” + b);             }     }

Output:

Strings before swap: a = Hello and b = World

Strings after swap: a = World and b = Hello

### Java Binary to Decimal conversion: Integer.parseInt()

The Integer.parseInt() method converts string to int with given redix. The signature of parseInt() method is given below:

1. publicstatic int parseInt(String s,int redix)

Let’s see the simple example of converting binary to decimal in java.

1. publicclass BinaryToDecimalExample1{
2. publicstatic void main(String args[]){
3. String binaryString=”1010″;
4. intdecimal=Integer.parseInt(binaryString,2);
5. out.println(decimal);
6. }}

Output:

10

### Java Decimal to Binary conversion: Integer.toBinaryString()

The Integer.toBinaryString() method converts decimal to binary string. The signature of toBinaryString() method is given below:

1. publicstatic String toBinaryString(int decimal)

Let’s see the simple example of converting decimal to binary in java.

1. publicclass DecimalToBinaryExample1{
2. publicstatic void main(String args[]){
3. out.println(Integer.toBinaryString(10));
4. out.println(Integer.toBinaryString(21));
5. out.println(Integer.toBinaryString(31));
6. }}

Output:

101010101

### 10 .  Write a Java program for matrix multiplication .

Let’s see a simple example to multiply two matrices of 3 rows and 3 columns.

In case of matrix multiplication, one row element of first matrix is multiplied by all columns of second matrix.

1. publicclass MatrixMultiplicationExample{
2. publicstatic void main(String args[]){
3. //creating two matrices
4. inta[][]={{1,1,1},{2,2,2},{3,3,3}};
5. intb[][]={{1,1,1},{2,2,2},{3,3,3}};
6. //creating another matrix to store the multiplication of two matrices
7. intc[][]=new int[3][3];  //3 rows and 3 columns
8. //multiplying and printing multiplication of 2 matrices
9. for(inti=0;i<3;i++){
10. for(intj=0;j<3;j++){
11. c[i][j]=0;
12. for(intk=0;k<3;k++)
13. {
14. c[i][j]+=a[i][k]*b[k][j];
15. }//end of k loop
16. out.print(c[i][j]+” “);  //printing matrix element
17. }//end of j loop
18. out.println();//new line
19. }
20. }}

Output:

6 6 6

12 12 12